Method of preparing electrolytes.



1o soda in solution is used as of the oxid of zinc,

tion.

UNITED STATES Patented July 7, 190a FFICE.

PATENT STORAGE BATTERY COMPANY,

A CORPORATION OF ILLINOIS.

METHOD OF PREPARING ELECTROLYTES.

SPECIFICATION forming part of Letters lPatent No. 732,843, dated my 7,1903.

Application filed January 23, 1902.

H To all whom it may concern.-

' Be it known that I, WILLIAM GARDINER, a citizen of the United States,residing at Ohicago, in the county of (look and State of Illi- 5 nois,have inventednew and useful Improvements in Methods of PreparingElectrolytes, of which the following is a specification.

In electric storage or secondary batteries of that type in which causticpotash or caustic the electrolyte and v in which one of the electrodesis a support upon which zinc is deposited one great disadvantage is theWeight and bulk of the electrolyte. Such an electrolyte has been here- I5 tofore produced by dissolving an oxid of zinc in a solutionof hydrateof sodium and hydrate of potassium. A solution of hydrate of potassiumor hydrate of sodium is capable of dissolving but a relatively smallquantity and in order to obtain a secondary battery of this characterhaving any considerable capacity it has heretofore been necessary toemploy in each case an exceedingly large quantity or volume of solu-This has made such secondary batteries very heavy and bulky inproportion to their effectiveness.

In carrying out my invention I use suitable electrodes. Any of thewell-known elecl trodes employed in this class of battery, however, maybe used, such as oxid of copper, for example, as the negative electrodeand a support of copper gauze or iron gauze upon which the zinc isdeposited in the charge as the posi- -tive electrode. i

, I produce my improved electrolyte by means of a strong solution,preferably of pure caustic potash, in which I dissolve pure oxid of zincmade by the wet process. This solution is placed in the cells of abattery having suitable electrodes and subjected to a charging-currentin the well-known way until the greater portion of the zinc contained inthe solution is deposited upon the positive ele- 145 ment. This solutionis then removed from the cells and placed .in a suitable receptacle forholding it temporarily. Oxid of zinc is then again dissolved in thissolution and the solution replaced in the same cellsas before Serial No.90,941. (No specimens.)

and a charging-current applied and the Zinc deposited as before. Thismay be repeated and the process continued until zinc sufficient to equalthe capacity of the desired battery is deposited or accumulated upon thepositive. electrode. When a sufficient quantity of zinc 5 is depositedupon the positive electrode, the solution used to dissolve the oxid ofzinc may be removed and a strong fresh solution of pure caustic potashand water containing no zinc oxid substituted. The battery is then inreadiness for discharge and charge in the performance of work. Duringthe discharge the zinc accumulated upon the positive electrode in theprior charges dissolves or is taken up in the solution, so that afterthe discharge is completed a far greater quantity of zinc is dissolvedor contained into this solution than could be possible by the oldprocess, which consists in dissolving an oxid of zinc in this samesolution before placing it in the battery.

Inasmuch as the excessive bulk and Weight of the ordinary battery ofthis type is caused by the capacity of the alkaline solution ordinaril yto take up, absorb, or otherwise con- 7 5 tain but a relatively smallquantity of oxid of zinc, necessitating a large quantity of solution forany battery having any considerable output it is obvious that by themethod described an electrolyte for this type of bat- 8o tery may beobtained which is very much reduced in weight and bulk, primarilybecause a sufficient quantity of zinc for a given capacity ofbattery-cell may be deposited in the charge upon the positive elementand dissolved into the solution on the discharge. Obviously, also, acell containing an electrolyte of the class described may be very muchmore quickly charged than in the ordinary cell of its kind, inasmuch asthe electrolyte contains a great excess of zinc, which is held insolution in an unstable condition and which is therefore depositedalmost immedt ately when the charging-current is applied.

I claim as my invention 5 The method of accumulating an excess depositof a metal, upon an electrode by re peatedly charging a cell containingin solution an oxid of the metal and a caustic alkali scribed my name inthe presence of two suband replenishing the oxid in the solutionbescribing witnesses. v tween successive chares, then when suffl- 1cient of the metal has fieen deposited replen- WILLIAM GARDINER' ishingthe cell with a solution of the pure In presence of caustic-alkalinesolution. C. W. HILLS,

In witness whereof I have hereunto sub- ANNA B. HILLS.

